Wall drive silo unloader



Patented dan. l, 1953 3,071,263 WALL DRIVE SILO UNLOADER George B. Bruecker, 1412 Oak Ridge, Kaulrauna, Wis. Filed May 27, 1960, Ser. No. 32,404 11 Claims. (Cl. 214-17) This invention relates to improvements in silo unloaders, and more particularly to a silo unloader having an improved drive mechanism for its rotary collector ann.

Heretofore, mechanical silo unloaders of the type utilizing a rotary collector arm have had relatively complex gear and sheave arrangements in order to drive said collector arm around the silo. Such drive mechanisms not only substantially increase the cost of the machine, but it has been found that they are subject to clogging and frequent mechanical breakdowns, and have otherwise proven unsatisfactory for `their intended function. With this in mind, therefore, the principal object of the present invention is to provide a silo unloader having a simplified drive mechanism which is not only less expensive, but which is more efficient, durable, and reliable than the drive arrangements employed in conventional unloaders.

A more specic `object of the present invention is to provide a silo unloader wherein the rotary collector arm is ldriven through the frictional engagement of its outer end portion with the wall of the silo, which Wall drive arrangement eliminates the necessity for a separate gear track assemblage and provides a greatly simplied and improved machine.

A further object of the present invention is to provide a silo unloader having an improved suspension and supporting system wherein the entier assemblage is always properly positioned in the silo, and wherein the supporting members will not become fouled or tangled while the machine is in operation.

Still `further objects of the present invention are to provide an improved silo unloader which is dependable in operation, which is rugged and durable, and which is well adapted for its intended purposes.

With the above and other objects in view, the invention consists of the improved silo unloader and all of its parts and combination as set forth in the following specification and claims, `and all equivalents thereof. v

In the accompanying drawing, illustrating the preferred form of the invention, and wherein like reference characters designate the same parts in all of the views:

FIG. 1 is a fragmentary vertical sectional View of a silo showing, in side elevation, the improved unloader in operative position therein;

vbe seen that the automatic silo unloader comprising the present invention includes a telescopic supporting shaft having a cable 11 attached to its upper end. Said cable is extended over a pulley (not shown) on the silo roof, and may be secured to a power winch so that the machine can be easily and quickly raised and lowered in the silo. The lower end of 4said supporting shaft 1@ is in the form of a yoke 17 and supports a platform 12 on which an electric motor 13 or -other prime mover is mounted. The motor drive shaft 14 projects downwardly through said platform 12 a substantial distance and has idrivably Amounted thereon both the lateral conveyor 15 and rotary collector 16, the design and operation of which members will be hereinafter described in greater detail.

The illustrated silo 18 is of the conventional cylindrical type and includes a row of vertically spaced doorways '19 extending the entire height of the silo, and a silage discharge chute 'Ztl attached to the silo exterior adjacent said doorways. Normally, the doorways are provided with removable doors which are taken out one at a time as the level of the silage descends, and during the unloading operation the silage is discharged through the nearest doorway and into the chute 20. It may be preferred, however, to utilize the special, bowed doors 21 and interior chute 21 described in my copending application Serial No. 820,656, liled June 16, 1959, and it is to be understood that the improved machine comprising the present invention can be used with either type of chute and for this reason both have been illustrated herein.

The lateral conveyor 15 hereinabove mentioned is preferably in the `form of an auger, -although an endless belt type conveyor might also be employed, and is drivably connected to the lower portion of the motor drive shaft 14 through a pair of coacting beveled gears 22 and 23 formed on the drive shaft 14 and conveyor shaft 24, respectively. Said conveyor shaft 2d projects radially outwardly from the motor drive shaft in a circumferentially fixed position and is telescopic in design, having an end portion 24 longitudinally slidably adjustably carried therein. A helical blade 25 is formed on said shaft 24 and is designed to convey silage deposited thereon by the rotary collector radially outwardly to the discharge chute when the machine is in operation, as Will be described.

The power communicating gears 22 and 23 are carried in a housing or gear box 26, and as will be seen in FIG. l, the lower end of the drive shaft 14 is extended downwardly through the said housing and has a pair of angularlydisposed, blade-like arms 27 and 2S thereon. When the machine is in operation said blades spin with the drive shaft and function to loosen and cut a path in the silage beneath the gear box, thereby permitting the unimpaired descent of said box as the machine travels downwardly with the level of the silage. In addition, said spinning blades provide a protective shield which prevents silage from finding its Way into the gear box and clogging or damaging the gear mechanism.

The rotary collector 16 featured in the present invention comprises an arm-like device mounted on and adapted to revolve around the motor drive shaft 14 in spaced relation above the lateral conveyor 15. Said rotary collector assemblage includes a longitudinally-adjustable supporting arm 31 and a laterally-disposed endless belt or chain 29 having a plurality of spaced, projecting fingers 30 thereon, the adjustable nature of said arm permitting its longitudinal adjustment to conform exactly to the radius of the particular silo in which the machine is to be used. The inner end of said arm is mounted for free rotation on and about the motor drive shaft 14 as mentioned, and the inner end of the chain is trained about a sprocket wheel 32. which is rigid on, and revolves with, said drive shaft. The outer end of said chain is trained `about a sprocket wheel 33 carried by a shaft 34 depending from the outer end of the arm 31, and mounted on and above said arm outer end portion is the Wall drive mechanism employed in the preferred form of the invention.

'It has heretofore been believed necessary to employ a special gear ring or track in silo unloaders of the general type described in order to provide positive means for driving the collector arm around the silo, which form of driving structure is expensive, mechanically inefficient, and subject to frequent operational difliculties. With this in mind, the present collector arm is designed to frictionally and drivably engage directly with the inner surface of the silo wall, thereby eliminating the necessity for a separate gear ring and greatly simplifying and increasing the efliciency of the arm driving mechanism.

As will be seen in FIG. 3, the shaft 34 on which the sprocket wheel 33 is mounted projects upwardly and has a sprocket 35 rigid on its upper portions, while mounted radially inwardly therefrom, and drivably connected thereto by a chain 37, is another, larger sprocket 36. Mounted on and above, and rotating with said sprocket 36 is a small gear 38, which engages and actuates the larger, wall-engaging wheel 39 which is mounted on and for free rotation about the shaft 34, said gear and wheel members having intermeshing cogs 40 and 41, respectively. The function of said coacting sprockets and gears 35, 36 and 3S, of course, is to reduce the speed of rotation of the initial sprocket wheel 33, which is driven off the motor drive shaft through the chain 29, to a slower speed permitting the driving wheel 39 to firmly engage the silo wall, and thereby driving the collector arm around the silo at a reduced pace where it will more effectively gather and convey the silage.

The driving wheel 39 has `a resilient rubber exterior, and when a portion of its peripheral surface reaches the point at which it pressurably engages the silo wall the cogs 41 thereon are deflected or deformed, thereby providing a multiplicity of gripping members to enhance the engagement of said wheel with the relatively smooth surfaces of the Wall. Moreover, the resilient nature of the driving wheel permits the same to yield somewhat on contact with protrusions or imperfections in the wall surface, which is advantageous in most silos where the wall surfaces are only rough finished.

In connection with the foregoing description of the rotary collector arm employed in the preferred form of the invention, it is to be understood that the exact design of said arm is not critical to the operation of the machine and the invention is not to be limited in this respect. It is contemplated, for example, that an auger type collector arm might be preferred for some uses and in such instances the wall-engaging wheel can be drivably connected to the auger shaft through coacting beveled gears or `any other suitable power communicating mechanism.

Rigidly mounted on and extending radially outwardly in the opposite direction from the rotary collector arm 16 is a guide member 42 designed to apply outward pressure on the collector arm to insure the rm engagement of the driving Wheel 39 thereon with the silo wall at all times. Said guide member comprises a hallow tube or sleeve 53 having -a compression spring 43 therein (FIG. 1), and a guide wheel 44 on its outer end adapted to ride on the inner surface of the silo wall at a point diametrically opposite the collector arm driving wheel 39. As illustrated in FG. l, the wheel-mounting fork is slidably carried within the sleeve 53 and has an elongated stem which abuts the aforementioned spring 43 and normally maintains the same in a semi-compressed state, said spring providing constant pressure on the driving wheel 39 to maintain the same firmly engaged with the silo wall. The spring action therein makes said guide member selfadjusting, of course, and it has been found that the machine operates effectively, therefore, even in silos which are out of round, or which have unusually irregular wall surfaces. lIn addition to the longitudinally-movable nature of said wheel-mounting fork 45 within the sleeve 53, said fork is also rotatably carried Within said sleeve, thereby permitting the driving wheel 44 to pivot freely. Thus, said driving wheel can swing from the horizontal position shown, which is its normal operating position, to a vertical position when the machine is being raised or lowered in the silo.

Referring `again to FIG. l, it will be seen that the collector arm is supported by means of a pair of diverging stays or cables 46 which can be either flexible or rigid and which are attached at their upper ends to a rotatable collar 47 carried on the main supporting shaft 10, and at their lower ends to the collector arm 16 and guide member 4Z intermediate their lengths. Said collar 47 is seated on a circumferential shoulder 48 formed on the shaft and is adapted to rotate freely on said shaft to permit the entire collector arm and guide member assemblage to travel around the silo without interference and without said cables `becoming fouled or tangled.

A stabilizing bar 49 is secured to and projects radially outwardly from the shaft 10 immediately above said rotatable collar 47 and is designed to give additional support to the entire assemblage. Said bar is rigid on the center shaft, there being -a supporting brace 49 therebetween, and projects radially outwardly therefrom to the silo wall in alignment with the doorway openings. Said bar 49 is telescopic in form, having an outer end portion 49 longitudinally-slidably, adjustably carried within and projecting outwardly beyond said bar proper, and attached to and depending from the outer end of said bar end portion 49 is a thin plate 50 having a twofold function. Said plate provides the support means for the outer end of the lateral conveyor 15 and, in addition, as shown in FIG. 2, the plate is curved to conform to the contour of the silo wall and is designed to cover the doorway openings so that the drive and guide `wheels 39 and 44 will pass thereover. In those silos utilizing the bow-shaped doors and interior silage discharge chute disclosed in my aforementioned copending application Serial No. 820,656, the plate is designed to ride within the door tracks 51 on the inner surface of the silo wall, thereby insuring the accurate positioning of the machine and preventing the same from inadvertently shifting while in use.

In the operation of the improved silo unloader cornprising the present invention, the machine is lowered into a silo through a suitable winch and cable device until the lateral conveyor is embedded in the silage and the rotary collector is resting on the surface thereof, and the machine is positioned with the outer end of the lateral conveyor adjacent the discharge chute. As the motor drive shaft l14, revolves, the collector chain 29 turns, being trained over the sprocket 32 on said drive shaft, and, simultaneously the coacting sprocket-s and gears 33, 35, 36 and 38 on the outer end of the collector arm turn the driving wheel 39 and the entire arm is caused to revolve circumferentially around the silo. As said arm revolves, the moving chain 29 and attached fingers 30 engage and continuously move the upper surface of the feed inwardly and deposit the same on the lateral conveyor 15 therebelow. Said lateral conveyor then carries the silage dropped thereon by the rotary collector radially outwardly to the discharge chute, where it falls into a container or onto a conveyor and is transported to the livestock feeding stations.

The principal features of the present invention, of

course, is the concept of a rotary collector arm which drivably engages directly with the silo Wall, and the consequent elimination of special gear ring or track assemblages. Such a drive mechanism is not only less expensive than such conventional drive systems, but is more efficient and reliable in operation, yand is less susceptible to mechanical failures. a A further advantage in the present machine is that the improved suspension and supporting means employed therein insures that the entire assemblage is always properly positioned in the silo, and eliminates the danger of the machine inadvertently shifting during operation, as sometimes occurs with conventional unloaders. The result is an automatic silo unloader which is both novel and practical, and which is unusually well suited for its intended use.

It is to be understood, and as hereinabove mentioned, that the improved silo unloader comprising the present invention is not to be limited or confined to the exact structural details of the individual components shown and described. Obvious modifications in the individual members will suggest themselves to persons skilled in the art, and all of such changes or modifications are contemplated which do not depart from the spirit of the invention and which may come within the scope of the following claims.

What I claim is:

l. A silo unloader for use in a cylindrical silo, comprising: a frame member positionable adjacent the top surface of the silage; a prime mover supported by said frame member, said prime mover having a depending drive shaft 4positionable centrally in the silo; means `for raising and lowering said frame member in the silo; a silage collector arm projecting radially from and mounted for rotation about said drive shaft, said arm being engageable with the top surface of the silage; a driving wheel on and extending beyond the outer end of said collector arm drivably engageable with the inner surface of the silo wall; power communicating means operatively connecting said driving wheel to the drive shaft; means connected to said collector arm pressurably engageable with another portion of the silo wall to maintain said driving wheel in firm engagement with said wall; and means supported by said frame and operatively associated with said prime mover adapted to convey silage accumulated by said collector arm to the silo exterior.

2. A silo unloader for use in a cylindrical silo, comprising: a frame; a motor supported on said frame, said motor having a drive shaft depending therebelow and positionable centrally in the silo; a lateral convey-or operatively connected to and projecting radially outwardly from the lower end portion of said motor drive shaft in a circumferentially fixed position; a collector arm mounted for free rotation on and around said motor drive shaft above said lateral conveyor, said arm projecting radially outwardly from said drive shaft to a point adjacent the silo wall; movable silage gathering means carried by said collector arm and drivably connected to said drive shaft; a driving member mounted on the outer end of said collector arm and operatively associated with said drive shaft, said driving member being drivably engageable with the inner surface of the silo wall and being adapted to drive said collector arm circumferentially around the silo; and means connected to said collector arm pressurably engageable with another portion of the silo wall to maintain said driving member in rm engagement with said wall.

3. In combination with a cylindrical silo having a row of vertically spaced doorway openings, an automatic silo unloader comprising: a frame; a motor supported on said frame, said motor having a drive shaft depending therebelow; a lateral conveyor operatively connected t-o and projecting radially outwardly from the lower end portion of said motor drive shaft in a fixed position in alignment ywith the silo doors; a collector arm mounted for free rotation on and around said motor drive shaft above said lateral conveyor, said arm projecting radially outwardly from said drive shaft to a point adjacent the silo wall; an endless chain carried by said collector arm, the inner end of said chain being drivably trained about a sprocket wheel rigidly mounted on said drive shaft and the outer end thereof being trained about a sprocket wheel carried by the outer end of said collector arm; silage gathering means on said chain; a driving member having a resilient surface mounted on the outer end of said collector arm; means interconnecting said outer sprocket wheel and said driving member, said driving member being drivably engageable with the inner surface of the silo wall and being adapted to drive the collector arm circumferentially Aaround the silo; and means connected to said collector arm pressurably engaging another portion of the silo wall to maintain said driving member in firm engagement with said Wall.

4. In combination with a cylindrical silo having a row of vertically spaced doorway openings, an automatic silo unloader comprising: a frame; means for raising and lowering said frame in the silo; a motor supported on said frame, said motor having a drive shaft depending therebelow; a lateral conveyor operatively connected to and projecting radially outwardly from the lower end portion of said motor drive shaft in a fixed position in alignment with the silo doors; a collector arm mounted for free rotation on and around said motor drive shaft above said lateral conveyor, said arm projecting radially outwardly from said drive shaft to a point adjacent the silo Wall; an endless chain carried by said collector arm, thel inner end of said chain being drivably trained about a sprocket wheel rigidly mounted on -said drive shaft and the outer end thereof being trained about a sprocket Wheel carried by the outer end of said collector arm; silage gathering means on said chain; reduction gears mounted on the outer end of said collector arm and operatively associated with said outer sprocket wheel; a driving wheel having a resilient surface and a plurality of peripheral cogs mounted on the outer end of said collector arm and operatively associated with said reduction gears, said wheel drivably engaging the inner surfacel of the silo wall and being adapted to drive the collector arm circumferentially around the silo; a guide member rigidly secured to said collector ar-m and projecting radially outwardly in the opposite direction therefrom, said guide member including a sleeve, a compression spring in said sleeve, a wheel fork slidably carried in said sleeve and normally maintaining said spring in a state of compression, and a guide wheel carried by said wheel fork and adapted to ride on the inner surface of the silo wall; and supporting means rotatably secured at their upper ends to said frame and -secured at their lower ends to said collector arm and guide members.

5, In a combination with a cylindrical lsilo having a row of vertically spaced doorway openings, an automatic silo unloader comprising: a telescopic vertical supporting shaft having a forked lower end; a cable attached to the upper end of said supporting shaft and secured to the silo roof; a motor platform supported by said shaft forked lower end; a motor mounted on said platform, said motor having a drive shaft depending therebelow; a lateral conveyor operatively connected to and projecting radially outwardly from the lower end portion of said motor drive shaft in a fixed position in alignment with the silo doors; a collector `arm mounted for free rotation on and around said motor drive shaft above said lateral conveyor, said arm projecting radially outwardly from said drive shaft to a point adjacent the silo wall; an endless chain carried by said collector arm, the inner end of said chain being drivably trained about a sprocket wheel rigidly mounted on said drive shaft and the outer end thereof being trained about a sprocket wheel carried by the outer end of said collector arm; silage gathering means on said chain; reduction gears mounted on the outer end of said collector arm and operatively associated with said outer sprocket wheel; a driving wheel having a resilient surface and a plurality of peripheral cogs mounted on the outer end of said collector arm and operatively associated with said reduction gears, said wheel drivably engaging the inner surface of the silo wall and being adapted to drive the collector arm circumferentially around the silo; a guide member rigidly secured to said collector arm and projecting radially outwardly in the opposite direction therefrom, said guide member including a sleeve, a compression spring in said sleeve, a wheel fork slidably carried in said sleeve and normally maintaining said spring in a state of compression, and a guide wheel carried by said wheel fork andadapted to ride on the inner surface of the silo wall; supporting cables rotatably secured at their upper ends to said vertical supporting shaft, and secured at their lower ends to said collector arm and guide members; a horizontal stabilizer bar rigidly secured to and projecting radially outwardly from the upper portion of said supporting shaft in alignment with said lateral conveyor, the outer end o-f said bar abutting the silo wall; and a plate depending from the outer end of said stabilizer bar and supporting the outer end of said lateral conveyor, said plate being curved to conform to the contour of the silo wall and being adapted to cover said doorway openings to permit said collector arm and guide member wheels to pass thereover.

6. A silo unloader of the type operable on the top surface of silage in a silo, comprising: a vertically-movable frame; a Collector arm supported by said frame, said co1- lector arm projecting radially outwardly from the center of the silo to a point adjacent the silo wall, and said co1- lector arm being mounted for free rotation about the center of the silo; power means on said unloader; movable silage gathering means carried by said collector arm and drivably connected to said power means; power take off means mounted on the outer end of said collector arm and operatively associated with ysaid movable silage gathering means; a drive member mounted on and extending beyond the outer end of said collector arm and rotatably drivably connected to said power take ot means, said drive member being drivably engageable with the inner surface of the silo wall, and said drive member being adapted to drive said collector arm circumferentially around the silo; and means on said unloader below said collector arm operatively connected to said power means adapted to convey silage gathered by said collector arm to the silo exterior.

7. ln a silo unloader of the type operable on the top surface of silage in a silo, and having a frame and a rotatable silage collecting arm connected to the frame, the improvement comprising: a drive wheel on the end of said collecting arm, said drive wheel being mounted on a vertical axis and being directly engage ble with the inner surface of the silo wall; power means on said unloader for driving said wheel; a second arm rotatably mounted on said frame and located approximately 18 from said silage collecting arm, said second arm including resilient biasing means; a guide wheel rotatably and pivotally mounted on the outer end of said second arm and adapted to engage the inner surface of the silo wall, said guide wheel being located rearwardly in the direction of rotation of said second arm from the longitudinal center line of said second arm, and said second arm and guide wheel assemblage being adapted to urge the drive wheel on the outer end of the collector arm into firm engagement with the inner surface of the silo wall.

8. A silo unloader of the type operable in a cylindrical silo having vertically aligned doorway openings therein, comprising: a vertical shaft positioned centrally in the silo; a lateral conveyor connected to said central shaft and projecting radially outwardly therefrom to a point adjacent the silo wall, said lateral conveyor being positioned in alignment with the silo doorway openings; a collector arm projecting radially from and mounted for rotation about said central shaft above said lateral conveyor; a drive wheel on the outer end of said collector arm drivably engageable with the inner surface of the silo wall; power means on said unloader for driving said wheel; an extendible support arm rigidly connected to said `frame and projecting radially outwardly above said collector arm in alignment with said lateral conveyor; and a curved, rigid plate connected to and depending from the outer end of said extendible support arm and rigidly connected to the outer end of said lateral conveyor, said plate being curved in cross section to conform generally to the curvature of the silo wall, and said plate covering a portion of said silo doorway openings to permit said drive wheel to pass thereover.

9. In combination with a silo, .an automatic silo unloader comprising: a frame; a motor supported on said frame, said motor having a drive shaft depending therebelow; a collector arm mounted for free rotation on and around said motor drive shaft, said arm projecting radially outwardly from said drive shaft to a point adjacent the silo wall; an endless member carried by said collector arm, the inner end of said endless member being drivably trained about a support member mounted on said drive shaft, and the outer end of said endless member being trained about a support member carried by the outer end of said collector arm; silage gathering means on said endless member; a driving member mounted outwardly beyond said outer end, said driving member engaging the inner surface of the silo wall and being adapted to drive the collector arm circumferentially around the silo; means mounted on the outer end of said collector arm operably connecting said outer support member and said driving member; and means on said unloader operably connected to said power means for conveying silage gathered by said collector arm to the silo exterior.

10. A silo unloader' for use in a cylindrical silo comprising: a frame member positionable adjacent the top surface of the silage; a vertical shaft depending below said frame and positionable centrally in the silo; a silage collector arm projecting radially from and mounted for rotation about said central shaft, said arm being engageable with the top surface of the silage; a driving member on and extending beyond the outer end of said collector arm driv ably engageable directly with the inner surface of the silo wall; a prime mover operatively associated with said driving member; a silage conveyor extending radially outwardly from said central shaft to said silo wall beneath said collector arm; and means operatively connecting said silage conveyor to said prime mover.

11. A silo unloader for use in a cylindrical silo, comprising: a frame member positionable adjacent the top surface of the silage; a vertical shaft depending below said frame and positionable centrally in the silo; a prime mover rotatably drivably associated with said shaft; a silage collector arm projecting radially from and mounted for rotation about said central shaft, said arm being engageable with the top surface of the silage; reduction gears on said collector arm drivably associated with said central shaft; a drive wheel on and extending beyond the outer end of said collector arm operatively associated with said reduction gears and drivably engageable with the inner surface of the silo wall; biasing means associated with said collector arm for urging said drive wheel into firm engagement with the silo wall; and means supported `by said frame and operatively connected to said prime mover adapted to convey silage accumulated by said collector arm to the silo exterior.

References Cited in the ille of this patent UNITED STATES PATENTS 1,275,558 Holmgreen Aug. 13, 1918 2,445,056 Cordis July 13, 1948 2,678,241 Miller May 11, 1954 2,711,814 McCarthy June 28, 1955 2,718,969 Cordis Sept. 27, 1955 2,963,327 Seymour et al Dec. 6, 1960 FOREIGN PATENTS 1,032,110 France Mar. 25, 1953 

1. A SILO UNLOADER FOR USE IN A CYLINDRICAL SILO, COMPRISING: A FRAME MEMBER POSITIONABLE ADJACENT THE TOP SURFACE OF THE SILAGE; A PRIME MOVER SUPPORTED BY SAID FRAME MEMBER, SAID PRIME MOVER HAVING A DEPENDING DRIVE SHAFT POSITIONABLE CENTRALLY IN THE SILO; MEANS FOR RAISING AND LOWERING SAID FRAME MEMBER IN THE SILO; A SILAGE COLLECTOR ARM PROJECTING RADIALLY FROM AND MOUNTED FOR ROTATION ABOUT SAID DRIVE SHAFT, SAID ARM BEING ENGAGEABLE WITH THE TOP SURFACE OF THE SILAGE; A DRIVING WHEEL ON AND EXTENDING BEYOND THE OUTER END OF SAID COLLECTOR ARM DRIVABLY ENGAGEABLE WITH THE INNER SURFACE OF THE SILO WALL; POWER COMMUNICATING MEANS OPERATIVELY CONNECTING SAID DRIVING WHEEL TO THE DRIVE SHAFT; MEANS CONNECTED TO SAID COLLECTOR ARM PRESSURABLY ENGAGEABLE WITH ANOTHER PORTION OF THE SILO WALL TO MAINTAIN SAID DRIVING WHEEL IN FIRM ENGAGEMENT WITH SAID WALL; AND MEANS SUPPORTED BY SAID FRAME AND OPERATIVELY ASSOCIATED WITH SAID PRIME MOVER ADAPTED TO CONVEY SILAGE ACCUMULATED BY SAID COLLECTOR ARM TO THE SILO EXTERIOR. 